Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

Venera 4 was the first Venus probe built by the Lavochkin design bureau, although Lavochkin engineers retained the basic design layout of the earlier Korolev probes.

The spacecraft consisted of a main bus about 3.5 m high and a 383-kg lander probe designed to transmit data as it descended through the Venusian atmosphere. This capsule was designed to endure loads as high as 350 g and land on both land and liquid. For atmospheric entry, it was equipped with a thick ablative heatshield.

After a midcourse correction on 29 July 1967, Venera 4 approached Venus on 18 October and released the lander at 04:34 UT, immediately prior to entry of the bus. Parachuting into the planet's atmosphere, the lander turned on its scientific instruments 5 minutes later when the rate of descent lowered to 10 m per second (at 55 km altitude). The probe continued to transmit for 93 minutes as it slowly fell through the atmosphere.

Initially, Soviet scientists believed that the probe transmitted until contact with the surface. In reality, transmissions ceased at an altitude of 27 km when the high atmospheric pressure and temperatures crushed the probe.

The data implied that surface temperatures and pressure were 500 degrees Celsius and 75 atmospheres respectively. Venera 4's gas analyzers also found that the planet's atmosphere was composed of 90 to 95 percent carbon dioxide with no nitrogen. The spacecraft bus measured the planet's weak magnetic field and found no ring of radiation belts. It detected a very weak atmosphere of atomic hydrogen about 9,900 km above the planet. Venera 4 was the first spacecraft to transmit data from a planet's atmosphere.

Key Dates

12 Jun 1967: Launch

18 Oct 1967: Probe Release

Status: Success

Fast Facts

Venera 4 was the first spacecraft to sample and transmit data from the atmosphere of another planet.

It was the Soviet Union's first successful planetary mission.

The probe was designed to float since it was not known whether Venus had oceans.